1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor device or a nonvolatile semiconductor storage device. The present invention particularly relates to a method of manufacturing an insulating layer composing the semiconductor device or the nonvolatile semiconductor storage device.
2. Description of the Related Art
In recent years, along with the development of integrated circuits, a variety of high-function elements, and the like, miniaturization of the elements has also progressed. Consequently, thinning of insulating layers typified by gate insulating layers of transistors has also been considered. However, when the gate insulating layers are thinned, the effect of dielectric breakdown of the gate insulating layers becomes significant. Therefore, there is demand for insulating layers with favorable withstand voltage.
In general, it is known that favorable insulating layers can be obtained using a thermal oxidation method; however, since a high temperature treatment at about 1000° C. is necessary, glass substrates which are weak against heat cannot be used.
Accordingly, a technique in which thin insulating layers are manufactured by a relatively low temperature treatment using an oxygen radical has been researched. For example, in Patent Document 1: Japanese Published Patent Application No. 2002-170820, it is mentioned that using a high-frequency wave such as a microwave, high-density oxygen plasma is generated using a mixed gas containing at least oxygen, and an insulating films is formed on a silicon film surface using the oxygen radical generated by the oxygen plasma. It is also mentioned in Patent Document 1 that oxidation rate of the oxygen plasma can be increased by using a gas containing a rare gas, water (H2O), or the like in addition to oxygen.